Embodiments of the inventive concepts relate to methods for manufacturing a semiconductor device. More particularly, embodiments of the inventive concepts relate to methods for manufacturing a semiconductor device including a high-voltage transistor.
A low-voltage transistor and a high-voltage transistor may be used in a semiconductor device (e.g., a flash memory device) that needs a high voltage for performing program and erase operations. The low-voltage and high-voltage transistors provided in peripheral circuits of this semiconductor device may include gate insulating layers having thicknesses different from each other. Since the high-voltage transistor is driven by a high voltage, the gate insulating layer of the high-voltage transistor may be thicker than the gate insulating layer of the low-voltage transistor.